It is known to provide a seat restraint system such as a seat belt in a vehicle to restrain an occupant in a seat of the vehicle. In some vehicles, the seat restraint system may be a lap belt, a shoulder belt, or both. Typically, the lap belt and shoulder belt are connected together at one end. The seat restraint system includes a latch plate at the connected end. The seat restraint system also includes a buckle connected at one end by webbing or the like to vehicle structure. The buckle receives the latch plate to be buckled together. When the buckle and latch plate are buckled together, the seat restraint system restrains movement of the occupant to help protect the occupant during a collision.
It is also known to provide a seat belt tensioner in the seat restraint system for tensioning an occupant belt restraint in the event of sudden vehicle deceleration. An example of such a seat belt tensioner is disclosed in U.S. Pat. No. 5,492,368 to Pywell. In this patent, the seat belt tensioner has a housing with a piston slidably mounted therein and a seat belt reel attached to a shaft of the piston. The seat belt tensioner is operated by pushing a piston with pyrotechnically generated gas and mechanically translating that force into seat belt reeling to wind the belt and seat belt tensioning.
It is further known to provide seat belt tensioners as buckle pretensioners with various cable locking methods. For example, it is known to use a ball and ramped piston-locking method for a buckle pretensioner. However, the ball and ramped piston results in high loads from the buckle assembly through the cable and into the piston.
It is desirable to provide a new seat restraint tensioner for a buckle assembly in a seat restraint system of a vehicle. It is also desirable to provide a seat restraint tensioner that provides seat belt pretensioning for a seat restraint system of a vehicle. It is further desirable to provide a seat restraint tensioner for a seat restraint system in a vehicle that is less costly and has a smaller package.